(a) Field of the Invention
The present invention relates to an organic light emitting device.
(b) Description of the Related Art
Generally, an active matrix flat panel display includes a plurality of pixels for displaying images, and displays images by controlling the luminance of each pixel according to given information. One type of active matrix flat panel display device, an organic light emitting display, is a self-emissive display device having low power consumption, wide viewing angle, and high response speed. Therefore, organic light emitting display is being spotlighted as a dominant next-generation display device, possibly even more than liquid crystal display (LCD).
An organic light emitting device includes an organic light emitting element, which includes two electrodes with an emission layer disposed therebetween. Electrons injected from one of the electrodes and holes injected from the other electrode are combined in the light emitting layer to form excitons, and the excitons release energy and cause light to be emitted.
An organic light emitting device also includes a plurality of pixels such as a red pixel, a blue pixel, and a green pixel which, when combined, can display full-color images.
However, an organic light emitting device may have different light emitting efficiency depending on the light emitting material. That is, a material having low light emitting efficiency among red, green, and blue cannot represent the colors of a desired color coordinate. The material having low light emitting efficiency also makes it difficult to display a desired white color that is produced by combining red, green, and blue.
To improve light emitting efficiency of the light emitting material, a micro-cavity may be used. In a micro-cavity, light is repeatedly reflected between a reflection layer and a transflective layer that are separated by a predetermined distance (an optical path length) such that light of a specific wavelength is strengthened through constructive interference, while light of the remaining wavelengths is diminished through destructive interference. Accordingly, the luminance and the color reproducibility may be simultaneously improved at the display side. However, to represent full-color images using micro-cavities, the red pixel, green pixel, and blue pixel use optical path lengths corresponding to the wavelengths of each pixel. Forming the micro-cavities having different optical path lengths for each pixel requires multiple processes, causing the manufacturing processes of the organic light emitting device to be complicated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.